The present invention relates to document holders that support documents for ease of access and review by a user.
Extensive use has been made of a certain aspect of paper sheets and similarly responsive sheet material in the art of making one or more of the sheets stand at a substantially more vertical than horizontal angle for viewing and/or ease of handling. That aspect is the tendency of such sheets to resist bending if sufficient vertical curvature is imposed on the sheet. Document holders are well known in the prior art making use of this feature.
U.S. Pat. No. 5,505,421 describes a copyholder for mounting on a surface having a base for mounting and pivotal paper holding means comprised of two opposed curved portions forming a paper-receiving channel. The curved portions have s-shapes. In this particular document holder, the sole support for the document is from a lowest edge of the sheet to a short distance up from that edge. This is a particular advantage since the lowest edge of a document typically has a substantial margin and lets the person viewing the document do so without having to hold it up in the air to get an angled view of it.
U.S. Pat. No. 5,842,721 describes a paper sheet holder with a base plate, a paper sheet guiding plate, which is arcuate as viewed in a top plan (upper direction), a permanent magnet fixed at a convex side surface of the paper sheet guiding plate, and a movable permanent magnet movably and magnetically attracted by the curved outer wall surface at the concave surface of the paper sheet guiding plate. The guiding plate is fixed in a slanted orientation above the base plate. A paper sheet holder includes a base plate, a paper sheet guiding plate made of non-magnetic material, a plurality of permanent magnets embedded in the paper sheet guiding plate while being spaced  apart by a predetermined distance in a horizontal direction, and a plurality of movable permanent magnets spaced apart by a predetermined distance in a horizontal direction. The movable permanent magnets are magnetically attracted to both side surfaces or one side surface of the paper sheet guiding plate. The requirement of using aligned magnets for a document holder substantially increases its price where equivalent functions may be obtained using only a molded plastic device.
U.S. Pat. No. 4,125,243 describes a small sign holder with a flat base of resilient material and two projections. The first projection has a convex, sloped side surface, and the second projection has a corresponding concave, sloped side surface spaced from the convex side surface of the first projection. An arcuate wedge-shaped trough is formed between the side surfaces of the projections. The edge of a sign card or board is inserted in the trough and removably held upright thereby. The wedge shape of the trough and the resilient material of the base combine to firmly grip the edge of the sign card. This combination of two separated elements is a distinct disadvantage in that the elements must be particularly aligned and separated only within a certain range in order to obtain its stated benefits.
U.S. Pat. No. 5,864,977 describes a display apparatus for use with a fuel pump filler gun. The apparatus has a barrel, a head, and a handle, includes a clip. The clip has opposed retaining surfaces biased toward one another. The retaining surfaces are configured to grasp a display between the opposed retaining surfaces and hold the display spaced apart from the filler gun. The display apparatus further includes various techniques for attaching the clip to the filler gun or to a protective boot covering a portion of the filler gun. The display apparatus can provide an expanded display area beyond the limited area of the filler gun itself without interfering with the use of the filler gun during the fueling operation. This type of document holder demonstrates a spring force method of holding a document without substantial vertical bending of the sheet to be displayed.
U.S. Pat. No. 3,258,232 describes a formed support that causes a single sheet to be vertically curved by using two separated and slotted arms forming a substantial obtuse angle with respect to each other. This two-point contact method of document support is  relatively unreliable for non-rigid sheets as relaxation of the sheet vertical curvature can occur unless the arm thickness is substantially increased.
U.S. Pat. No. D418,166 shows a particularly popular document holder sold under the commercial name “Page Up”. Two slightly inclined continuous front and back surfaces connect with a floor section that has a higher elevation at the ends of the slot than at the middle part of that floor section. This configuration lets the user insert a single page that leans slightly away from the user. The slight declination of the paper (which is typically of about 30 pound weight or less) combined with a lateral curvature, i.e., a slight U-shape when viewed from above, causes results in a good view of the paper with stable support. However, in the commercial embodiment, a substantial weight is contained in the device of this patent to support the weight of multiple sheets of paper. A sand or fluidized solid material must be contained in the device to prevent its falling over when the paper support slot holds up to about the maximum of about 20 sheets of paper.
The art of document holding is necessarily connected with aesthetics and design. The pleasant appearance of a document holder, which can be produced at low cost, makes it more economically viable as a product that a user will want to place on their workspace. The above and other prior art devices have not adequately combined the functional and pleasing aspects of document holders for one or more documents. There is a need for a document holder that can hold one or more sheets that presents to the user a pleasant and interesting design.